Self-cleaning washing machine

ABSTRACT

A self-cleaning washing machine includes an inner drum, an outer drum and a chamber defined therebetween. The chamber is provided with cleaning pellets rotatable with water flow for cleaning walls of the inner and outer drums. An inner surface of the bottom of the outer drum includes at least one structure of: an inclined area formed on the inner surface along a circumferential direction with a height near a center of the bottom of the outer drum higher than that near a side wall of the outer drum; an annular water channel formed on the inner surface, being adjacent to the side wall of the outer drum, and recessed along the circumferential direction; and a water blocking convex rib formed on the inner surface corresponding to a side of the water drainage port along a rotation direction of the inner drum during dewatering.

FIELD OF THE INVENTION

The present invention relates generally to washing machines, and more particularly, to a self-cleaning washing machine in which drum walls between inner and outer drums are automatically cleaned by cleaning pellets placed between the inner and outer drums and rotatable with water flow.

BACKGROUND OF THE INVENTION

In existing wave wheel washing machines, the environment between inner and outer drums is closed, and only water can flow through. Due to limitations from the washing machine structure and the particularity of the user environment, dirt adheres to the outer wall of the inner drum and the inner wall of the outer drum after three to five months of use. Consequently, bacteria will breed in different extents, most of which are harmful to human body.

As people's living standards and the requirements of living quality increase, a solution to the sanitation of washing machines seems to be urgent. A survey conducted by a related scientific research institution on the internal environment of washing machines shows that consumers have started paying more and more attention to the severity of internal contamination of washing machines. To fundamentally prevent washing machines from bringing second-time dirt to the laundry and to be more responsible for users' health, the cleaning issue of the internal environment of washing machines needs to be addressed immediately.

Chinese Patent 200820183308.4 discloses a sleeve washing machine with walls between the drums cleaned. The washing machine includes an inner drum, an outer drum, and multiple circular silicone balls for cleaning the walls between the inner and outer drums. During washing, the inner drum rotates to drive water to flow, thereby driving the silicone balls between the inner drum and outer drum of the washing machine to move and continuously collide with the walls between the inner and outer drums, so as to achieve the objective of cleaning the walls between the inner and outer drums.

By using the washing machine structure as described above, however, rubber balls or soft pellets are freely scattered in the drum after water drainage, which causes big noises during the high speed dewatering process, and also increases energy consumption and affects the service life of the washing machine.

In addition, Chinese Application No. 201010160548.4 discloses a washing machine using soft pellets to clean the environment between inner and outer drums of the washing machine and a method thereof. In the washing machine, soft pellets are placed between the inner and outer drums of the washing machine, and when laundry is washed, water flows regularly to drive the soft pellets to collide and rub the walls between the inner and outer drums of the washing machine, so as to clean the environment between the inner and outer drums of the washing machine.

However, the washing machine structure as described above has the following disadvantages: If the soft pellets are kept between the inner and outer drums, loud noise is produced during dewatering of the washing machine as the soft pellets collide with the inner and outer drums, and the pellets are also damaged, leading to a decrease in the pellets and affecting the cleaning effects. If the cleaning pellets are discharged during water drainage, for the structure, it is difficult to discharge all the pellets, and some pellets still remain during dewatering. In addition, because a gap between the bottom of the inner drum and the bottom of the outer drum is small, it is difficult for water to flush between the bottoms of the inner and outer drums after use for a long time, and much dirt accumulates and is not easily removed. Therefore, with the cleaning pellets in the structure, self-cleaning of the bottom area of the inner drum cannot be implemented effectively.

Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.

SUMMARY OF THE INVENTION

One of the objectives of the present invention is to provide a self-cleaning washing machine in which the bottom of an outer drum is configured to increase a water flow velocity during water drainage so as to discharge cleaning pellets, thereby, solving the foregoing problems and disadvantages.

In one aspect of the present invention, a self-cleaning washing machine includes an inner drum, an outer drum, and a chamber defined between the inner drum and the outer drum. The chamber is provided with cleaning pellets rotatable with water flow for cleaning an inner wall of the outer drum and an outer wall of the inner drum. An inner surface of the bottom of the outer drum is provided with one or more of the following improvment structures:

a first improvement structure: an inclined area formed on the inner surface of the bottom of the outer drum along a circumferential direction, where a height of the inclined area near a center of the bottom of the outer drum is higher than that near a side wall of the outer drum, and a water drainage port is disposed at a lowest point of the bottom of the outer drum;

a second improvement structure: an annular water channel formed on the inner surface of the bottom of the outer drum, being adjacent to the side wall of the outer drum, and recessed along the circumferential direction, wherein the water drainage port on the bottom of the outer drum communicates with the annular water channel; and

a third improvement structure: a water stopping convex rib formed on the surface of the bottom of the outer drum and corresponding to a side of the water drainage port along a rotation direction of the inner drum during dewatering.

In one embodiment, the height of the inner surface of the bottom of the outer drum gradually decreases along a radial direction from the center to the side wall of the outer drum, and the bottom of the outer drum is of a cone-shaped structure having a center higher than its periphery.

In one embodiment, he height of the inner surface of the bottom of the outer drum gradually decreases along a clockwise or counter-clockwise circumferential direction, and a decreasing direction of the height is relevant to the rotation direction of the inner drum of the washing machine during dewatering.

In one embodiment, an inclination angle a between the inner surface of the bottom of the outer drum along the radial direction and a horizontal plane satisfies with 0<α<30°.

In one embodiment, an inclination angle a between the inner surface of the bottom of the outer drum along the radial direction and a horizontal plane satisfies with 0<α<3°, and a height difference between a highest point and a lowest point during the gradual decrease along the circumferential direction is 5 to 30 mm or is 1/10 to ⅓ of a minimum spacing between the bottom of the inner drum and the bottom of the outer drum.

In one embodiment, a depth of the annular water channel gradually decreases along a clockwise or counter-clockwise circumferential direction, a decreasing direction of the depth is relevant to the rotation direction of the inner drum of the washing machine during dewatering, the water drainage port is disposed at a lowest point of the annular water channel, and a side of the water drainage port is adjacent to a shallowest point of the annular water channel.

In one embodiment, a width of the annular water channel gradually increases along the clockwise or counter-clockwise circumferential direction, a changing direction of the width is relevant to the rotation direction of the inner drum of the washing machine during dewatering, the water drainage port is disposed at a widest point of the annular water channel, and the side of the water drainage port is adjacent to a narrowest point of the annular water channel.

In one embodiment, the annular water channel gradually decreases and inclines from the center of the bottom of the outer drum to the side wall of the outer drum, and is formed by matching the side wall of the outer drum.

In one embodiment, the annular water channel has a width of 10 to 60 mm and a depth of 3 to 15 mm.

In one embodiment, the water stopping convex rib comprises a radial convex rib from the center of the bottom of the outer drum to a side of the water drainage port, and the radial convex rib is tangent to the side of the water drainage port.

In one embodiment, the water stopping convex rib comprises an arc-shaped convex rib from the center of the bottom of the outer drum to a side of the water drainage port, and the arc-shaped convex rib smoothly transits an outline of the side of the water drainage port.

In one embodiment, the water stopping convex rib has a height of 5 to 20 mm.

In one embodiment, the water stopping convex rib is formed by a section of a height difference between a highest connecting point and a lowest connecting point that are obtained when the surface of the bottom of the outer drum gradually decreases in height along a clockwise or counter-clockwise circumferential direction.

According to the present invention, using the cleaning pellets placed between the inner and outer drums to clean the walls of the inner and outer drums is based on a principle that washed objects in the inner drum rub the inner drum so that the inner drum has no dirt adhered thereon and no bacteria breeding thereon. The cleaning pellets may be sponge type objects, or may be rubber or plastic foamed objects, such as foamed rubber, foamed plastic, and foamed composite polyurethane. In certain embodiments, an absorptive material is used so that better drum wall cleaning effects are achieved. In certain embodiments, the cleaning pellets are elastic to some extent, have a smaller density than water when being dry, have a soakage feature in water, and be cheap. Even though the cleaning pellets are not reused and are discharged each time, the costs are not high.

In certain embodiments, the cleaning pellets are ball-shaped, block-shaped, ellipsoid-shaped, cylinder-shaped, or regular tetrahedron-shaped, or are other irregular mass-like pellets, a quantity of which is 10 to 50. These pellets have a smaller density than water, and are elastic and abrasion resistant to some extent.

According to the present invention, after the washing machine completes washing, to avoid noises produced by colliding the cleaning pellets between the inner and outer drums with the drum walls during high speed dewatering and a decrease in the service life of the inner and outer drums, during water drainage and before high speed dewatering, the cleaning pellets are discharged with water through the water drainage port or are collected for reuse. To save a resource and reduce costs, it is preferable to reuse the cleaning pellets in the washing machine according to the present invention. In certain embodiments, a water drainage apparatus is disposed below the outer drum of the washing machine, and communicates with the water drainage port. The apparatus collects the cleaning pellets by using discharged water during water drainage and dewatering, and while stopping the cleaning pellets, smoothly discharges lint, sheet-like objects such as coins and buttons, and other sundries smaller than the cleaning pellets, thereby avoiding blockage. When water is fed next time, the cleaning pellets float upwards with the rise of the water level, get out of the water drainage apparatus and enter the chamber between the inner and outer drums through the water drainage port, and continue to rotate with water to clean the drum walls between the inner and outer drums.

According to the embodiments of the self-cleaning washing machine, in a water drainage process and/or a dewatering process, the inner drum is controlled to perform different actions, so that the cleaning pellets flow with washing water into the water drainage port and are collected by the water drainage apparatus or are directly discharged. In the water drainage process, the inner drum is controlled to rotate at a low rotation speed of 5 to 50 revolutions per minute, so that cleaning pellets clamped between the walls of the inner and outer drums fall between the inner and outer drums, and flow with water in the outer drum into the water drainage port. At the dewatering stage, the inner drum is controlled to brake at least once, so that cleaning pellets clamped between the walls of the inner and outer drums fall between the inner and outer drums, and flow with water throw out of clothing into the water drainage port.

In view of the foregoing, the present invention, compared with the prior art, has the following beneficial effects.

According to the embodiments of the washing machine of the present invention, in a washing process, because the wave wheel or the inner drum continuously rotates in forward and reverse directions, water in the outer drum is exchanged with water in the inner drum to form water flow, to drive the cleaning pellets in the chamber between the inner and outer drums to move in the water, collide with and rub the walls of the inner and outer drums, and also remove, with the help of soakage by the water, attachments on the walls of the inner and outer drums and the bottom part of the inner drum, which fundamentally prevents accumulation of dirt and eliminates bacteria breeding. When a user washes clothing, the inner and outer drums are cleaned at the same time. Washing and cleaning are synchronous, no dirt remains, and cleanliness and comfort are provided.

The improved structures of the bottom of the outer drum according to the embodiments of the present invention are a structure in which the surface of the bottom of the outer drum inclines and gradually decreases in height from the center of the bottom of the outer drum to the circumferential direction, a structure of inclination and gradual decrease in height along a direction consistent with the and the rotation direction during dewatering, a structure of a circumferentially annular water channel, and a structure of a water stopping convex rib on a side of the water drainage port. With these structures, cleaning pellets on the surface of the bottom of the outer drum all can flow with water into the water drainage port during water drainage, avoiding noise produced because some cleaning pellets are left in the outer drum and the cleaning pellets collide with the drum walls during dewatering.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of the inner and outer drums of the washing machine according to one embodiment of the present invention.

FIG. 2 is a schematic diagram of the bottom of the outer drum of the washing machine according to one embodiment of the present invention.

FIG. 3 is a sectional view along A-A direction in FIG. 2.

FIG. 4 is a sectional view along B-B direction in FIG. 2.

FIG. 5 is a schematic structural diagram of the outer drum according to one embodiment of the present invention.

FIG. 6 is a schematic structural diagram of the bottom of the outer drum according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present invention are further described in detail hereinafter with reference to the accompanying drawings.

As shown in FIG. 1, the washing machine according to one embodiment of the present invention includes an outer drum 1, an inner drum 2, and a chamber 3 defined between the outer drum 1 and the inner drum 2. The chamber 3 is provided with cleaning pellets 4 for cleaning drum walls. In a washing/rinsing process, water flow drives the cleaning pellets in the chamber 3 between the inner and outer drums to move, collide with and rub the walls of the inner and outer drums, and also remove, with the help of soakage by water, attachments on the walls of the inner and outer drums and the bottom part of the inner drum. To avoid noises caused by colliding the cleaning pellets between the inner and outer drums with the drum walls at a stage of high speed dewatering of clothing, the cleaning pellets need to be discharged or collected for reuse.

In the washing machine according to certain embodiments of the present invention, the cleaning pellets are collected for reuse. A pellet collecting apparatus is disposed below a water drainage port of the washing machine, and stops the cleaning pellets and collects the cleaning pellets below the water drainage port each time of water drainage. Discharged water includes water discharged during dewatering. When water is fed next time, the cleaning pellets float depending on the buoyancy of the water, and enter the chamber between the inner and outer drums from the water drainage port. In a water drainage process, the inner drum is controlled to rotate at a low rotation speed of 5 to 50 revolutions per minute, so that cleaning pellets clamped between the walls of the inner and outer drums fall between the inner and outer drums, and flow with water in the outer drum into the water drainage port. At a dewatering stage, the inner drum is controlled to brake at least once, so that cleaning pellets clamped between the walls of the inner and outer drums fall between the inner and outer drums, and flow with water throw out of clothing into the water drainage port. During water drainage, the inner drum rotates along a same direction at a low rotation speed to drive water to rotate, the centrifugal force of the water acts on an inner wall of the outer drum, and when the water level decreases to the water drainage port on the bottom, the water first flows into the water drainage port on the bottom under the action of the centrifugal force. The inner drum rotates at a same direction at the dewatering and water drainage stages.

As shown in FIG. 2, according to one embodiment of the present invention, an inner surface of the bottom 5 of the outer drum is configured, so that the cleaning pellets easily flow with water into a water drainage port 6 during water drainage. In the water drainage process, the inner drum rotates. The improvement on the bottom 5 of the outer drum includes one of or a combination of the following four structures: structures 10 and 11 in which the surface of the bottom of the outer drum inclines and gradually decreases in height, a structure of an annular water channel 12 circumferentially disposed on the bottom of the outer drum, and a structure of a water stopping convex rib 13 on a side of the water drainage port 6.

EMBODIMENT 1

As shown in FIGS. 2 and 3, in this exemplary embodiment, the improvement structure on the bottom of the outer drum is of the structure 10 in which the surface of the bottom of the outer drum inclines and gradually decreases in height along a radial direction from a center 8 of the bottom of the outer drum to a side wall 9 of the outer drum, where the inner surface of the bottom 5 of the outer drum is provided with a surface inclined area 7. The inclined area 7 is formed along a circumferential direction. A height of the inclined area 7 near the center 8 of the bottom of the outer drum is higher than that near the side wall 9 of the outer drum. The water drainage port 6 of the washing machine is disposed at a lowest point of the bottom of the outer drum. This structure helps discharged water to flush the cleaning pellets into the water drainage port during water drainage, especially when there is little water at the end of the water drainage.

In one embodiment, the surface inclined area 7 is of a structure whose height gradually decreases from the center 8 of the bottom of the outer drum to the periphery. Specifically, a height of the inner surface of the bottom 5 of the outer drum gradually decreases along the radial direction from the center 8 to the side wall 9 of the outer drum, and the bottom 5 of the outer drum is of a cone-shaped structure having a center is higher than its periphery. In one embodiment, an inclination angle a between the inner surface of the bottom 5 of the outer drum along the radial direction and a horizontal plane satisfies with 0<α<30° (as shown in FIG. 3).

In one embodiment, the surface inclined area is an annular area, and a relationship between a radial width L of the annular area, that is, a difference between an outer radius and an inner radius of the annular area, and a radius R of the bottom of the outer drum satisfies with: R/5<L<R.

EMBODIMENT 2

As shown in FIGS. 2 and 4, in this embodiment, the improvement structure on the bottom of the outer drum is of the structure 11 of inclination and gradual decrease in height along a direction consistent with the circumferential direction and the rotation direction of the inner drum during dewatering, where the height of the inner surface of the bottom 5 of the outer drum gradually decreases along a clockwise or counter-clockwise circumferential direction, and a decreasing direction of the height is consistent with the rotation direction of the inner drum of the washing machine during dewatering. Generally, an existing rotation direction of an inner drum of a washing machine during dewatering is a clockwise direction, and therefore, the height of the inner surface of the bottom 5 of the outer drum gradually decreases clockwise (as shown in FIG. 2). The water drainage port 6 is disposed at a lowest point 14 of the bottom of the outer drum, and a side of the water drainage port 6 is adjacent to a highest point 15. This structure not only helps to discharge the cleaning pellets during water drainage, but also helps water that is thrown out of clothing before high speed dewatering to flush cleaning pellets possibly remaining in the outer drum when the water is discharged, where the cleaning pellets are generally clamped between the inner and outer drums when the water level decreases after water drainage, and falls on the bottom of the outer drum because of rotation of the inner drum.

Specifically, a height difference H between the highest point 15 and the lowest point 14 when the height of the inner surface of the bottom 5 of the outer drum gradually decreases along the circumferential direction is 5 to 30 mm or is 1/10 to ⅓ of a minimum spacing between the bottom of the inner drum and the bottom of the outer drum.

EMBODIMENT 3

This embodiment is a combination of EMBODIMENTS 1 and 2. A change in the height of the inner surface of the bottom of the outer drum is gradually decreasing along the circumferential direction while gradually decreasing along the radial direction from the center to the periphery. This structure better helps to discharge the cleaning pellets with water into the water drainage port during water drainage.

In the foregoing embodiments, the inner surface of the bottom of the outer drum has an inclined structure, where potential energy brought by an inclination height difference is converted into water flow energy, to increase the impact power of water, and prevent the cleaning pellets from remaining on the inner surface of the bottom of the outer drum.

EMBODIMENT 4

As shown in FIGS. 2 and 5, in this embodiment, the improvement structure on the bottom of the outer drum is of a concave annular water channel 12 disposed along the circumferential direction on a part of the bottom 5 of the outer drum that is adjacent to the side wall 9 of the outer drum, and the water drainage port 6 communicates with the annular water channel 12. Preferably, the water drainage port 6 is disposed in the annular water channel 12, or the annular water channel 12 runs through the water drainage port 6 (as shown in FIG. 5).

Further, a depth of the annular water channel 12 gradually decreases along the clockwise or counter-clockwise circumferential direction, a decreasing direction of the depth is consistent with the rotation direction of the inner drum of the washing machine during dewatering, the water drainage port 6 is disposed at a lowest point of the annular water channel 12, and a side of the water drainage port is adjacent to a shallowest point of the annular water channel; and/or a width of the annular water channel 12 gradually increases along the clockwise or counter-clockwise circumferential direction, a changing direction is consistent with the rotation direction of the inner drum of the washing machine during dewatering, the water drainage port 6 is disposed at a widest point of the annular water channel, and a side of the water drainage port is adjacent to a narrowest point of the annular water channel.

Further, the annular water channel 12 has a width of 10 to 60 mm and a depth of 3 to 15 mm, or the annular water channel 12 has a width of 1/30 to ⅕ of the radius of the bottom of the outer drum.

In combination with EMBODIMENT 1, the annular water channel 12 in this embodiment gradually decreases in height and inclines from the center 8 of the bottom of the outer drum to the side wall 9 of the outer drum, and is formed by matching the side wall 9 of the outer drum.

EMBODIMENT 5

As shown in FIGS. 2 and 6, as the water drainage port 6 has two sides 61 and 62 along the circumferential direction on the bottom 5 of the outer drum, and the rotation direction of the inner drum during dewatering is generally a clockwise direction, the side 61 is against the rotation direction of the inner drum during dewatering, that is, a side the water drainage port that is first traveled by during rotation; and the other side 62 is along the rotation direction of the inner drum during dewatering, that is, a side of the water drainage port that is later traveled by during rotation. In this embodiment, a water stopping convex rib 13 is disposed on the surface of the bottom 5 of the outer drum and corresponding to the side 62 of the water drainage port 6 that is along the rotation direction of the inner drum during dewatering (as shown in FIG. 2). During dewatering and water drainage, the inner drum rotates to drive water to rotate along one direction, and the water stopping convex rib 13 stops the water so that an enlarged water drainage vortex is formed at the water drainage port 6, increasing a flow velocity and helping the cleaning pellets to enter the water drainage port 6.

The water stopping convex rib 13 comprises a radial convex rib from the center 8 of the bottom of the outer drum to the side 62 of the water drainage port, and the radial convex rib is tangent to the side 62 of the water drainage port.

Alternatively, the water stopping convex rib 13 comprises an arc-shaped convex rib from the center 8 of the bottom of the outer drum to the side 62 of the water drainage port, and the arc-shaped convex rib smoothly transits an outline of the side 62 of the water drainage port.

The water stopping convex rib 13 in this embodiment has a height of 5 to 20 mm or 1/10 to ½ of a space defined between the bottom of the inner drum and the bottom of the outer drum.

EMBODIMENT 6

This embodiment is a combination of EMBODIMENTS 2 and 5. In this embodiment, the water stopping convex rib 13 is formed by a section of a height difference between a highest connecting point and a lowest connecting point that are obtained when the surface of the bottom of the outer drum gradually decreases in height along the clockwise or counter-clockwise circumferential direction (as shown in FIG. 6), the water drainage port 6 is disposed at the lowest point 14 of the bottom of the outer drum, and the side 62 of the water drainage port 6 that is along the rotation direction of the inner drum during dewatering is adjacent to the highest point 15.

EMBODIMENT 7

This embodiment is a combination of EMBODIMENTS 1, 2, 4, and 5. In this embodiment, the structure improvement on the bottom of the outer drum includes all of: the structure 10 in which the surface of the bottom of the outer drum inclines and gradually decreases in height along the radial direction from the center 8 of the bottom of the outer drum to the side wall 9 of the outer drum, the structure 11 of inclination and gradual decrease in height along a direction consistent with the circumferential direction and the rotation direction of the inner drum during dewatering, the structure of the annular water channel 12 circumferentially disposed on the bottom of the outer drum, and the structure of the water stopping convex rib 13 on the side of the water drainage port 6 (referring to FIG. 2).

The improved structures of the bottom of the outer drum according to the present invention help to discharge the cleaning pellets, especially at the end of water drainage and during dewatering. In an existing flat structure of the bottom of the outer drum, cleaning pellets are easily left on the bottom of the outer drum when there is little water. With the structures according to the present invention, the flow velocity and flushing force of water are increased, and all the cleaning pellets can be discharged.

While there has been shown several and alternate embodiments of the present invention, it is to be understood that certain changes can be made as would be known to one skilled in the art without departing from the underlying scope of the present invention as is discussed and set forth above and below including claims. Furthermore, the embodiments described above and claims set forth below are only intended to illustrate the principles of the present invention and are not intended to limit the scope of the present invention to the disclosed elements. 

1. A self-cleaning washing machine, comprising: an inner drum; an outer drum; and a chamber defined between the inner drum and the outer drum, wherein the chamber is provided with cleaning pellets rotatable with water flow for cleaning an inner wall of the outer drum and an outer wall of the inner drum, wherein an inner surface of the bottom of the outer drum is provided with one or more of the following improvement structures: a first improvement structure: an inclined area formed on the inner surface of the bottom of the outer drum along a circumferential direction, wherein a height of the inclined area near a center of the bottom of the outer drum is higher than that near a side wall of the outer drum, and a water drainage port is disposed at a lowest point of the bottom of the outer drum; a second improvement structure: an annular water channel formed on the inner surface of the bottom of the outer drum, being adjacent to the side wall of the outer drum, and recessed along the circumferential direction, wherein the water drainage port on the bottom of the outer drum communicates with the annular water channel; and a third improvement structure: a water blocking convex rib formed on the surface of the bottom of the outer drum and corresponding to a side of the water drainage port along a rotation direction of the inner drum during dewatering.
 2. The self-cleaning washing machine according to claim 1, wherein the height of the inner surface of the bottom of the outer drum gradually decreases along a radial direction from the center to the side wall of the outer drum, and the bottom of the outer drum is of a cone-shaped structure having a center higher than its periphery.
 3. The self-cleaning washing machine according to claim 1, wherein the height of the inner surface of the bottom of the outer drum gradually decreases along a clockwise or counter-clockwise circumferential direction, and a decreasing direction of the height is relevant to the rotation direction of the inner drum of the washing machine during dewatering.
 4. The self-cleaning washing machine according to claim 1, wherein an inclination angle a between the inner surface of the bottom of the outer drum along the radial direction and a horizontal plane satisfies with 0<α<30°.
 5. The self-cleaning washing machine according to claim 3, wherein an inclination angle a between the inner surface of the bottom of the outer drum along the radial direction and a horizontal plane satisfies with 0<α<3°, and a height difference between a highest point and a lowest point in the gradual decrease along the circumferential direction is 5 to 30 mm or is 1/10 to ⅓ of a minimum spacing between the bottom of the inner drum and the bottom of the outer drum.
 6. The self-cleaning washing machine according to claim 1, wherein a depth of the annular water channel gradually decreases along a clockwise or counter-clockwise circumferential direction, a decreasing direction of the depth is relevant to the rotation direction of the inner drum of the washing machine during dewatering, the water drainage port is disposed at a lowest point of the annular water channel, and the side of the water drainage port is adjacent to a shallowest point of the annular water channel.
 7. The self-cleaning washing machine according to claim 1, wherein a width of the annular water channel gradually increases along the clockwise or counter-clockwise circumferential direction, a changing direction of the width is relevant to the rotation direction of the inner drum of the washing machine during dewatering, the water drainage port is disposed at a widest point of the annular water channel, and the side of the water drainage port is adjacent to a narrowest point of the annular water channel.
 8. The self-cleaning washing machine according to claim 1, wherein the annular water channel gradually decreases and inclines from the center of the bottom of the outer drum to the side wall of the outer drum, and is formed by matching the side wall of the outer drum.
 9. The self-cleaning washing machine according to claim 1, wherein the annular water channel has a width of 10 to 60 mm and a depth of 3 to 15 mm.
 10. The self-cleaning washing machine according to claim 1, wherein the water blocking convex rib comprises a radial convex rib from the center of the bottom of the outer drum to the side of the water drainage port, and the radial convex rib is tangent to the side of the water drainage port.
 11. The self-cleaning washing machine according to claim 1, wherein the water blocking convex rib comprises an arc-shaped convex rib from the center of the bottom of the outer drum to the side of the water drainage port, and the arc-shaped convex rib smoothly transits an outline of the side of the water drainage port.
 12. The self-cleaning washing machine according to claim 10, wherein the water blocking convex rib has a height of 5 to 20 mm.
 13. The self-cleaning washing machine according to claim 10, wherein the water blocking convex rib is formed by a section of a height difference between a highest connecting point and a lowest connecting point that are obtained when the surface of the bottom of the outer drum gradually decreases in height along a clockwise or counter-clockwise circumferential direction. 